Control of the inflammatory response in extended myocardial preservation of the donor heart

Hypothermia-Triggered Mesoporous Silica Particles for Controlled Release of Hydrogen Sulfide to Reduce the I/R Injury of the Myocardium

Despite the fact that heart transplantation (HTx) is a relatively mature procedure, heart ischemic and reperfusion (I/R) injury during HTx remains a challenge. Even after a successful operation, the heart will be at risk of primary graft failure and mortality during the first year. In this study, temperature-sensitive polymer poly(N-n-propylacrylamide-co-N-tert-butyl acrylamide) (PNNTBA) was coated on diallyl trisulfide (DATS)-loaded mesoporous silica nanoparticles (DATS-MSN) to synthesize hypothermia-triggered hydrogen sulfide (H₂S) releasing particles (HT-MSN). Because the PNNTBA shell dissolves in phosphate-buffered saline at 4 °C, the loaded DATS could continuously release H₂S within 6 h when activated by glutathione (GSH). Furthermore, after co-culturing biocompatible HT-MSN with cardiomyocytes, H₂S released from HT-MSN at 4 °C was found to protect cardiomyocytes from ischemic and reperfusion (I/R) injury. In detail, the rate of cell apoptosis and lactate dehydrogenase activity was decreased, as manifested by increased BCL-2 expression and decreased BAX expression. More importantly, in an isolated heart preservation experiment, HT-MSN demonstrated potent protection against cardiac I/R injury and reduced expression of inflammatory factors TNF-α and IL-1β. This study provided a new method for the controlled release of H₂S by the donor and myocardial protection from I/R injury.

Ischemic reperfusion injury-induced oxidative stress and pro-inflammatory mediators in liver transplantation recipients

OBJECTIVE

Liver ischemic reperfusion injury is harmful to transplant recipients, and is associated with postoperative morbidity and mortality. Our study was designed to investigate the oxidative stress and pro-inflammatory mediators in liver transplant recipients.

METHODS

We prospectively analyzed 14 recipients who underwent liver transplantation by measuring their blood levels of malondialdehyde (MDA) and cytokines, such as tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6, at nine time points perioperatively. We also evaluated the correlations between oxidative stress (MDA levels) and the characteristics of the recipient or the donated graft.

RESULTS

These parameters significantly increased from 1 minute before reperfusion, and the values peaked within 3 to 30 minutes after reperfusion. On the time point at 5 minutes after reperfusion, the MDA levels which were the highest in the recipients correlated with the values of preoperative direct/and total bilirubin, aspartate aminotransferase (AST), alanine aminotransferase (ALT), model for end-stage liver disease (MELD) score, international normalized ratio (INR), and surgical blood loss.

CONCLUSION

The levels of MDA, TNF-α, IL-1β, and IL-6 greatly increased with the ischemic reperfusion insult. Recipients with higher values of preoperative direct/and total bilirubin, AST, ALT, MELD score, INR, and surgical blood loss tended to have higher levels of MDA and may suffer more injury from this insult.

MicroRNA and mRNA signatures in ischemia reperfusion injury in heart transplantation

Ischemia reperfusion (I/R) injury is an unavoidable event occurring during heart transplantation, leading to graft failures and lower long-term survival rate of the recipient. Several studies have demonstrated that microRNAs (miRNAs) are vital regulators of signalling pathways involved in I/R injury. The present study aims to quantify the altered expression levels of miRNA and mRNA upon I/R injury in a mouse heart transplantation model, and to investigate whether these miRNA can regulate genes involved in I/R injury. We performed heterotopic heart transplantation on mouse models to generate heart tissue samples with I/R and non-I/R (control). The expression levels of miRNAs as well as genes were measured in heart grafts by microarray and real time RT-PCR. miRNA alteration in cardiomyocytes exposed to hypoxia was also detected by qRT-PCR. We observed significant alterations in miRNA and gene expression profile after I/R injury. There were 39 miRNAs significantly downregulated and 20 upregulated up to 1.5 fold in heart grafts with I/R injury compared with the grafts without I/R. 48 genes were observed with 3 fold change and p<0.05 and 18 signalling pathways were enriched using Keggs pathway library. Additionally, hypoxia/reperfusion induced primary cardiomyocyte apoptosis and altered miRNA expression profiles. In conclusion, this is the first report on miRNA expression profile for heart transplantation associated with I/R injury. These findings provide us with an insight into the role of miRNA in I/R injury in heart transplantation.

Successful transplantation of rat hearts subjected to extended cold preservation with a novel preservation solution

Since prolonged cold preservation of the heart deteriorates the outcome of heart transplantation, a more protective preservation solution is required. We therefore developed a new solution, named Dsol, and examined whether Dsol, in comparison to UW, could better inhibit myocardial injury resulting from prolonged cold preservation. Syngeneic heterotopic heart transplantation in Lewis rats was performed after cold preservation with UW or Dsol for 24 or 36 h. In addition to graft survival, myocardial injury, ATP content, and Ca(2+) -dependent proteases activity were assessed in the 24-h preservation group. The cytosolic Ca(2+) concentration of H9c2 cardiomyocytes after 24-h cold preservation was assessed. Dsol significantly improved 7-day graft survival after 36-h preservation. After 24-h preservation, Dsol was associated with significantly faster recovery of ATP content and less activation of calpain and caspase-3 after reperfusion. Dsol diminished graft injury significantly, as revealed by the lower levels of infarction, apoptosis, serum LDH and AST release, and graft fibrosis at 7-day. Dsol significantly inhibited Ca(2+) overload during cold preservation. Dsol inhibited myocardial injury and improved graft survival by suppressing Ca(2+) overload during the preservation and the activation of Ca(2+) -dependent proteases. Dsol is therefore considered a better alternative to UW to ameliorate the outcome of heart transplantation.

Heterotopic rat heart transplantation (Lewis to F344): early ICAM-1 expression after 8 hours of cold ischemia

BACKGROUND

Primary graft dysfunction is a still poorly understood complication after cardiac transplantation. Ischemia/reperfusion injury contributes to different disorders resulting in impaired graft function.

METHODS

In a heterotopic rat heart transplantation model we extended graft ischemic time up to 8 hours.

RESULTS

Using immunohistochemistry we detected an up to 4-fold increase in intracellular adhesion molecule-1 (ICAM-1) expression during 4 hours of reperfusion, independent of ischemic time (30-minute ischemia: 7.65 +/- 2.15 without reperfusion, 19.46 +/- 4.6 after 4-hour reperfusion; 240-minute ischemia: 5.6 +/- 1.99 and 22.3 +/- 3.77; 480-minute ischemia: 3.7 +/- 1.56 and 13.1 +/- 2.2). Eight-hour ischemic allografts had an increase in CD8-positive cells (1.37 +/- 0.5 and 2.3 +/- 0.77) and a significant increase in MHC II expression (11.48 +/- 2.1 and 18.27 +/- 1.34) during 4 hours of reperfusion.

CONCLUSIONS

We hypothesize that these findings reflect an early inflammatory reaction in the allograft possibly triggered by oxidative stress. During therapeutic interventions, both of these pathways must be considered.

Interstitial leukocytes in right ventricular endomyocardial biopsies after heart transplantation in patients with complicated versus uneventful postoperative course

BACKGROUND

Infections and rejections play key roles in morbidity and mortality in the early postoperative period after orthotopic heart transplantation (HTX). The aim of this study was to evaluate whether qualitative and quantitative analyses of various interstitial leukocytes in endomyocardial biopsies during the first 2 weeks after HTX provided early information on these complications.

PATIENTS AND METHODS

During and after HTX, endomyocardial biopsies were obtained in 51 patients. By immunohistochemistry we determined the CD3-, CD4-, CD8-, CD15-, CD20-, CD57-, and CD68-positive cell numbers projected to planimetrically measured areas. To compare morbidity in the postoperative course, the patients were subdivided into complicated versus uncomplicated after 3 months.

RESULTS

In the uncomplicated group, the cell counts of CD3-, CD8-, CD57-, and CD68-positive cells were significantly lower than in the complicated group. CD3-, CD4-, and CD8-positive cell numbers showed a significant decrease in the first week among the uncomplicated group. In the complicated group, the cell counts increased significantly in the second week. The numbers of CD57-positive cells were significantly lower during the first and second weeks among the uncomplicated group.

CONCLUSIONS

Increased T lymphocytes, natural killer cells, and macrophages observed in the second week after HTX indicated increased morbidity. A reduction in CD3-positive cells in the first week indicated a low morbidity risk; an increase indicated a higher risk.

The minimized extracorporeal circulation system causes less inflammation and organ damage

The minimized extracorporeal circulation system (MECC) is being used to reduce priming volume and blood/polymer contact during cardiac procedures. In this study, we evaluated the efficacy and potential advantages of the system in coronary artery bypass graft (CABG) patients. We included two groups of patients destined for CABG in a prospective, randomized study: Group A was operated on the usual pump (n = 30) while Group B was operated using the MECC (n = 50). Pre-operative demographics, intra-operative times and values as well as a series of post-operative outcome data (blood loss, transfusion requirements, ventilation time, ICU and hospital stay) were recorded. CK, CK-MB, troponin-T, IL-6 and IL-8 were measured. Pre-operative and post-operative lung function were assessed. In the MECC-operated group, patients developed less post-operative troponin-T (0.2 ± 0.3 vs. 0.5 ± 0.5 ng/mL, p=0.031) and less IL-8 (13.8 ± 5 vs. 22.5 ± 0.5 µg/L, p = 0.05). While blood loss was comparable in both groups, packed red blood cells and fresh frozen plasma were given less frequently in the MECC group (p = 0.015 resp. 0.022). The one-tailed Student’s t-test revealed shorter bypass time in the MECC group (74 ± 17 vs. 82 ± 24 min). There was no difference in ventilation and ICU-time (patients were not treated in a fast-track fashion). The FEV1 was better in the MECC group (relative values: 70.1 ± 18.2% vs. 61.1 ± 12.3%, p = 0.02). Utilization of the MECC may cause less cytokine (IL-8) liberation, owing to less blood/tubing contact, as well as less red blood cell and fresh frozen plasma demand. It may also be the circuit in patients with chronic obstructive pulmonary disease (COPD).

Hemoadsorption to Improve Organ Recovery from Brain-Dead Organ Donors: A Novel Therapy for a Novel Indication?

While brain-dead organ donors represent the majority of the organ donor pool, it appears that graft survival is adversely affected by brain death itself. Brain death has been shown to cause severe disturbances in the hormonal, hemodynamic and immunological homeostasis, which could in part be responsible for the inferior outcome of organs originating from brain-dead donors compared to living donors. Hemodynamic effects of brain death lead to a wide fluctuation in mean perfusion pressures, blood flow to the organs and systemic oxygen consumption, altering regional perfusion. In addition, a wide array of immunological changes has been shown to occur after brain death contributing to organ injury and hemodynamic instability. Recent studies have shown that brain death upregulates multiple lymphocyte- and macrophage-derived cytokines and the injured brain itself may be the source of proinflammatory factors such as S100B. This increased inflammatory response seen during and immediately after brain death has also been associated with poor allograft function. Furthermore, there is evidence to suggest that the massive inflammatory response seen in brain-dead donors could also lead to increased immunogenicity and accelerated allograft rejection after transplantation. Hence, we hypothesize that nonspecific downregulation of this inflammatory response by hemoadsorption could potentially lead to improved donor organ and allograft function. As a 'proof of concept' we tested the ability of a novel hemoadsorbent to remove S100B in vitro using two human glioblastoma cell lines. Our results indicate a >80% reduction in S100B after 2 h of circulation with the sorbent.

NOS substrate during cardioplegic arrest and cold storage decreases stunning after heart transplantation in a rat model

BACKGROUND

In this study, we evaluated how adding L-arginine to Centre de Résonance Magnétique Biologique et Médicale (CRMBM) solution affected myocardial performance during post-ischemic in vivo reperfusion.

METHODS

Experiments were conducted using a modified Lewis-Lewis heterotopic heart transplantation model, with a total ischemic time of 3 hours followed by 1 or 24 hours of blood reperfusion. Heart grafts were arrested using intra-aortic injection of CRMBM solution, either supplemented or not supplemented with 2 mmol/liter L-arginine (n = 12 in each group). We measured systolic indexes and simultaneously performed phosphorus magnetic resonance spectroscopy ((31)P MRS). We quantified total endothelial nitric oxide synthase (eNOS) protein using the Western blot test of freeze-clamped hearts.

RESULTS

Contractility during early reperfusion was significantly better in grafts arrested with CRMBM solution enriched with L-arginine: mean rate pressure product, 11249 +/- 1548 vs 5637 +/- 1118 mm Hg/min (p = 0.05), and maximal first derivative of the pressure signal (dP/dt(max)), 1721 +/- 177 vs 1214 +/- 321 mm Hg/sec (p = 0.013). Conversely, during late reperfusion, contractility did not relate to the nature of the preservation solution. The presence of L-arginine in the CRMBM solution did not alter time-related variations of high-energy phosphate ratios measured using in vivo (31)P MRS. The eNOS protein level decreased significantly during early compared with late reperfusion, with no effect caused by L-arginine.

CONCLUSIONS

During early reperfusion, the limited myocardial stunning observed with CRMBM solution containing L-arginine does not relate to energy metabolism but to better preservation of the NO pathway.

Gene expression profiling of prolonged cold ischemia and reperfusion in murine heart transplants

BACKGROUND

Heart transplantation causes complex changes in the biological homeostasis of the graft. Current knowledge is restricted to a few genes and regulation of certain factors involved in ischemia-reperfusion (I/R) injury. Efficient strategies to prevent I/R injury, however, require a better understanding of its mechanisms. Using cDNA microarrays, we investigated gene expression profiles of murine cardiac isografts.

METHODS

For microarray hybridization experiments, chips with 8,734 individual target sequences were used. Messenger RNA was extracted from hearts subjected to warm ischemia and different time periods of reperfusion or to prolonged cold ischemia or warm ischemia and transplantation. Native hearts served as controls.

RESULTS

A set of 68 sequences was regulated in all hearts. In addition, grafts without cold ischemia showed differential expression of 65 sequences, which were not found in hearts transplanted after cold storage, and which in turn had 38 sequences regulated and not detected in grafts without cold ischemia. Overall, approximately 50% of regulated transcripts are expressed sequence tags (ESTs) with unknown function. Annotated genes encoded immune modulators (20% of sequences), receptor proteins, structural proteins, and proteins involved in metabolism.

CONCLUSION

Our data demonstrate expression profiles of hearts subjected to prolonged cold ischemia or transplantation in an isogeneic setting. We have defined functional complexes and detected a substantial amount of ESTs encoding novel proteins. These studies may provide a molecular basis for further functional experiments and may help identify potential targets for modulation of postischemic inflammation.

A new in vitro model to study endothelial injury

BACKGROUND

Endothelial dysfunction or "endothelialitis" is a prominent feature in several disease states ranging from atherosclerosis to transplant rejection. This dysfunction is also caused by drugs such as cyclosporin A (CyA) and leads to allograft vasculopathy and eventual graft loss. Despite the frequency and importance of this injury, there is no model to study the morphological effects of endothelial injury and dysfunction in vitro.

METHODS

We utilized a model in which mouse endothelial cells (SVEC 4-10) can be induced to form capillary tubes by culturing on a laminin-rich matrix (Matrigel). In this morphological model of endothelial cell function, we studied the effect of varying doses of CyA on two parameters of tube formation: initiation of tube formation and disruption of mature capillary tubes. As a positive control we used IFN-gamma, which inhibited capillary tube formation. We developed this assay in 96-well culture plates to test several samples simultaneously.

RESULTS

The assay could be adapted to a 96-well format by optimizing the cell density. Endothelial dysfunction was seen when the endothelial cells were incubated with cyclosporin A, which affected both morphological parameters of tube formation. At higher doses (2-20 microg/ml) CyA both inhibited capillary tube formation and disrupted mature capillary tubes. At lower doses CyA only inhibited the initiation of tube formation; it did not disrupt mature capillary tubes. IL-2 (400-1000 pg/ml) and IFN-gamma (10-400 pg/ml) inhibited initiation of tube formation but did not disrupt mature capillary tubes. None of these agents, including high doses of CyA, impaired endothelial cell viability.

CONCLUSION

CyA-induced endothelial dysfunction can be modeled in vitro by this novel morphological assay of capillary tube formation. This assay can discern mild and severe degrees of endothelial dysfunction. The different effects of low and high levels of CyA on capillary tube formation imply that similar dysfunction in vivo may be responsible for allograft vasculopathy caused by CyA. This novel model can also be utilized to study other forms of vasculitis.

The interleukin-6/interleukin-6-receptor system is activated in donor hearts

OBJECTIVES

To assess the potential of the donor heart to respond to interleukin-6 (IL6), the present study investigated the expression of IL6 receptor components in the myocardium of donor hearts before transplantation.

BACKGROUND

Donor heart dysfunction early after transplantation has been associated with the cytokine storm after donor brain death. Proinflammatory cytokines are thought to play a central role in this process. Interleukin-6 is of specific interest because it has been associated with cardiac allograft dysfunction and is related to an impaired prognosis. Its action requires expression of the specific IL6 receptor (IL6R), and the common signal transducer of the IL6 family glycoprotein 130 (gp130) in the donor heart.

METHODS

The activation of IL6, IL6R and gp130 messenger ribonucleic acid (mRNA) and protein was studied via reverse transcription-polymerase chain reaction (RT-PCR) and immunohistology in donor hearts (n = 6) and compared with patients undergoing evaluation of ventricular arrhythmias (control, n = 9) or with advanced heart failure (n = 20).

RESULTS

Messenger RNA of IL6, IL6R and gp130 was strongly expressed in all chambers of donor hearts, whereas right ventricles of control patients did not show any expression (donor vs. control: p < 0.005). Right ventricles of failing hearts showed IL6, IL6R and gp130 mRNA levels comparable with those found in donor hearts. Immunohistochemistry paralleled the RT-PCR data on the protein level. While IL6 was mainly expressed by myocytes, both receptor components were preferentially found mainly on interstitial cells.

CONCLUSIONS

The expression of the IL6 receptor components in the donor heart before transplantation establishes the condition sine qua non for the response of the donor heart to circulating IL6. This mechanism may explain the close association of elevated IL6 serum levels to acute cardiac allograft dysfunction in the early perioperative period.

The endothelium in clinical cardiac transplantation

Cardiac transplantation is the most successful therapy for refractory heart failure, but clinical transplantation is still confronted with the problems of acute rejection and acute pump failure. The limiting factor in achieving prolonged survival remains cardiac allograft vasculopathy. In recent years it has become apparent that from brain death onward, the cardiac endothelium plays a key role in these acute and chronic events. Brain death is associated with an inflammatory response that primes the endothelium for cumulative injury during the subsequent stages of ischemic cold storage, reperfusion and allorecognition. As a structural and functional interface, the endothelium is the site at which inflammatory cells move from the bloodstream through the vessel wall into the parenchyma. The endothelium interacts with the complement system, the coagulation and inflammatory cascades, circulating leukocytes, the immune system, the smooth muscle in the vessel wall, and the surrounding matrix and cardiomyocytes. A better understanding of its many roles may lead to expansion of our therapeutic possibilities and better outcomes overall. This article reviews the possible roles of the endothelium in relation to cardiac transplantation, and discusses the diagnostic and therapeutic modalities that are available to date.

Effect of a neutrophil elastase inhibitor (ONO-5046 Na) on ischemia/reperfusion injury using the left-sided heterotopic canine heart transplantation model

BACKGROUND

Ischemia/reperfusion injury is a major cause of transplanted heart dysfunction. Several reports have demonstrated that polymorphonuclear neutrophil (PMN) elastase derived from the activated neutrophils might play an important role in this injury. Herein, we investigated the protective effects of PMN elastase inhibitor (ONO-5046 Na) on ischemia/reperfusion injury using a left-sided canine heterotopic heart transplantation model.

METHODS

We used 10 pairs of adult beagle dogs. The donor heart was transplanted heterotopically into the left thoracic cavity of the recipient without cardiopulmonary bypass. A bolus of ONO-5046 Na (10 mg/kg) was introduced intravenously to 5 recipients (group II) at 15 minutes before reperfusion and was followed by continuous infusion (10 mg/kg per hour) for 180 minutes. Five dogs (group I) did not receive ONO-5046 Na and thus served as a control. After reperfusion, we evaluated transplanted heart function and obtained blood samples from the coronary sinus over a 360-minute period.

RESULTS

E(max) and pre-load recruitable stroke work in group II showed significantly better recovery than group I. Blood levels of PMN elastase, creatine kinase MB, lactate and inflammatory cytokines (tumor necrosis factor-alpha, interleukin-6, interleukin-8) were significantly lower in group II. Depletion of myocardial concentration of adenosine triphosphate at 120 minutes after reperfusion and myocardial water content was significantly lower in group II.

CONCLUSIONS

ONO-5046 Na, which inhibits PMN elastase, could reduce ischemia/reperfusion injury in heart transplantation. These results indicate that clinical application of ONO-5046 Na should be considered.

Theory and in vivo application of electroporative gene delivery

Efficient and safe methods for delivering exogenous genetic material into tissues must be developed before the clinical potential of gene therapy will be realized. Recently, in vivo electroporation has emerged as a leading technology for developing nonviral gene therapies and nucleic acid vaccines (NAV). Electroporation (EP) involves the application of pulsed electric fields to cells to enhance cell permeability, resulting in exogenous polynucleotide transit across the cytoplasmic membrane. Similar pulsed electrical field treatments are employed in a wide range of biotechnological processes including in vitro EP, hybridoma production, development of transgenic animals, and clinical electrochemotherapy. Electroporative gene delivery studies benefit from well-developed literature that may be used to guide experimental design and interpretation. Both theory and experimental analysis predict that the critical parameters governing EP efficacy include cell size and field strength, duration, frequency, and total number of applied pulses. These parameters must be optimized for each tissue in order to maximize gene delivery while minimizing irreversible cell damage. By providing an overview of the theory and practice of electroporative gene transfer, this review intends to aid researchers that wish to employ the method for preclinical and translational gene therapy, NAV, and functional genomic research.